Remove ScSpecTypeSet support, which was already mostly dead. #3241

Job	Run time
build-fuzz	2m 13s
build-fuzz	2m 13s
cargo-deny (advisories)	3m 31s
cargo-deny (advisories)	3m 31s
cargo-deny (bans licenses sources)	3m 16s
cargo-deny (bans licenses sources)	3m 16s
build-and-test (ubuntu-latest, x86_64-unknown-linux-gnu)	14m 49s
build-and-test (ubuntu-latest, x86_64-unknown-linux-gnu)	14m 49s
build-and-test (macos-latest, x86_64-apple-darwin)	2m 3s
build-and-test (macos-latest, x86_64-apple-darwin)	29m 17s
build-and-test (macos-latest, aarch64-apple-darwin)	18m 45s
build-and-test (macos-latest, aarch64-apple-darwin)	18m 45s
build-and-test (windows-latest, x86_64-pc-windows-msvc)	23m 31s
build-and-test (windows-latest, x86_64-pc-windows-msvc)	23m 31s
docs	5m 56s
docs	5m 56s
fmt	9s
fmt	9s
publish-dry-run	0s
publish-dry-run	0s
rust-analyzer-compat	9m 16s
rust-analyzer-compat	9m 16s
complete	1s
complete	1s
	3h 14m 14s

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